Can my x670e Motherboard support bifurcation?

[Hostile_18]

Hi all. I'm trying to work out if my X670e Carbon Wifi supports bifurcation so I can put a PCIE nvme expander in (slot 2 or 3, ideally 3). I can't seem to get a clear answer. I looked in bios and it has the options pictured but with its labelled "PCIe_e1" does this mean I can only add it to the first slot?

 

[Meddling-Monk]

I think it means bifurcation happens and that the first slot is left over to become a x8 slot with anything in PCI E2 slot getting the other x8. Or if all three slots are used, it goes to 8, 4, 4 or 4, 4, 4, 4. Although I don't know how that works without a fourth PCIe slot in that last one.

 

[Hostile_18]

I think it means bifurcation happens and that the first slot is left over to become a x8 slot with anything in PCI E2 slot getting the other x8. Or if all three slots are used, it goes to 8, 4, 4 or 4, 4, 4, 4. Although I don't know how that works without a fourth PCIe slot in that last one.

I might be wrong but I was under the impression x4x4x4x4 configuration would put the top pci slot able to read four devices at once on the top slot. I'll be putting a graphics card in the top one so that would be a no go. It certainly dosnt seem clear anywhere.

 

[hornetstinger]

it sucks that using PCI-E slots means reduced performance :-/

I'm using a PCI-E GPU in the top slot, then a Asus Xonair soundcard, then a NVME PCI-E adaptor. Does that mean some or all of the cards are being reduced in speed?

 

[Meddling-Monk]

I might be wrong but I was under the impression x4x4x4x4 configuration would put the top pci slot able to read four devices at once on the top slot. I'll be putting a graphics card in the top one so that would be a no go. It certainly dosnt seem clear anywhere.

Yeah, it's not super clear on the Asus Proart X670E either, but Asus has a specific article out that goes through it in more detail (in relation to the Asus boards) and that's what it appears to be what they're saying in that. But we all know how each motherboard maker does their own thing too, so even if it reads 100% the same, it might not act the same.

 

[Meddling-Monk]

it sucks that using PCI-E slots means reduced performance :-/

I'm using a PCI-E GPU in the top slot, then a Asus Xonair soundcard, then a NVME PCI-E adaptor. Does that mean some or all of the cards are being reduced in speed?

It depends on your CPU and motherboard lane assignment I think. Some older systems had it easier as the sound cards can go in x1 slots and not be a hassle. But more current motherboard designs appear to have dropped them (mostly) making it harder to determine if that's happening or not.

 

[Meddling-Monk]

I might be wrong but I was under the impression x4x4x4x4 configuration would put the top pci slot able to read four devices at once on the top slot. I'll be putting a graphics card in the top one so that would be a no go. It certainly dosnt seem clear anywhere.

Just to update, I think it's purely talking about the PCIe speed it drops to and not to the devices it reads. Else why would there be a 8/8 option as well? That should be talking about when PCIe5 1 and 2 are in use.

 

[Marak]

This seems to be an overlooked feature from MB vendors, its the same on my X870E Taichi Lite. The only bifurcation option is for the top slot, but it would be useful to have the 2nd slot as x4x4 if I wanted another optane drive for example.

Best bet may be to email your MB vendor and request the feature.

Alternately the add-on board itself would have to do the bifurcation on its own with the 2nd slot staying at x8. I understand there are some boards that can do that but have no experience myself.